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11.E: Reactions of Alkyl Halides: Nucleophilic Substitutions and Eliminations (Exercises)

  • Page ID
    61716
  • These are the homework exercises to accompany the Textmap for McMurry's Organic Chemistry textbook.

    11.1 The Discovery of Nucleophilic Substitution Reactions

    11.1 Exercises

    Questions

    Q11.1.1

    Predict the product of a nucleophilic substitution of (S)-2-bromopentane reacting with CH3CO2-, Show stereochemistry.

    Solutions

    S11.1.1

    11.3 Characteristics of the SN2SN2 Reaction

    11.3 Exercises

    Questions

    Q11.3.1

    What product(s) do you expect from the reaction of 1-bromopentane with each of the following reagents in an SN2 reaction?

    A – KI

    B – NaOH

    C - CH3C≡C-Li

    D – NH3

    Q11.3.2

    Which in the following pairs is a better nuceophile?

    A - (CH3CH2)2N- or (CH3CH2)2NH

    B - (CH3CH2)3N or (CH3CH2)3B

    C – H2O or H2S

    Q11.3.3

    Order the following in increasing reactivity for an SN2 reaction.

    CH3CH2Br CH3CH2OTos (CH3CH2)3CCl (CH3CH2)2CHCl

    Q11.3.4

    Solvents benzene, ether, chloroform are non-polar and not strongly polar solvents. What effects do these solvents have on an SN2 reaction?

    Solutions

    S11.3.1

    S11.3.2

    A - (CH3CH2)2N- as there is a charge present on the nitrogen.

    B - (CH3CH2)3N because a lone pair of electrons is present.

    C - H2O as oxygen is more electronegative.

    S11.3.3

    S11.3.4

    They will decrease the reactivity of the reaction.

    11.4 The SN1SN1 Reaction

    11.4 Exercises

    Questions

    Q11.4.1

    Give the products of the following SN1 reaction. Show stereochemistry.

    Solutions

    S11.4.1

    11.4.png

    11.5 Characteristics of the SN1SN1 Reaction

    11.5 Exercises

    Questions

    Q11.5.1

    Rank the following by increasing reactivity in an SN1 reaction.

    Q11.5.2

    3-bromo-1-pentene and 1-bromo-2-pentene undergo SN1 reaction at almost the same rate, but one is a secondary halide while the other is a primary halide. Explain why this is.

    Q11.5.3

    Label the following reactions as most likely occuring by an SN1 or SN2 mechanism. Suggest why.

    Solutions

    S11.5.1

    Consider the stability of the intermediate, the carbocation.

    A < D < B < C (most reactive)

    S11.5.2

    They have the same intermediates when you look at the resonance forms.

    S11.5.3

    A – SN1 *poor leaving group, protic solvent, secondary cation intermediate

    B – SN2 *good leaving group, polar solvent, primary position.

    11.7 Elimination Reactions: Zaitsev's Rule

    11.7 Exercises

    Questions

    Q11.7.1

    Ignoring the alkene stereochemistry show the elimination product(s) of the following compounds:

    Solutions

    S11.7.1

    11.8 The E2E2 Reaction and the Deuterium Isotope Effect

    11.8 Exercises

    Questions

    Q11.8.1

    What is the product of the following molecule in an E2 reaction? What is the stereochemistry?

    Solutions

    S11.8.1

    The stereochemistry is (Z) for the reaction.

    11.9 The E2E2 Reaction and Cyclohexane Conformation

    11.9 Exercises

    Questions

    Q11.9.1

    Which of the following compounds will react faster in an E2 reaction; trans-1-bromo-2-isopropylcyclohexane or cis-1-bromo-2-isopropylcyclohexane?

    Solutions

    S11.9.1

    The cis isomer will react faster than the trans. The cis isomer has two possible perpendicular hydrogen in which it can eliminate from.

    11.12 A Summary of Reactivity: SN1SN1, SN2SN2, E1E1, E1E1cB, and E2E2

    11.12 Exercises

    Questions

    Q11.12.1

    Label the following reactions as SN1, SN2, E1, or E2.

    Solutions

    S11.12.1

    A – SN2

    B – E1

    C – SN1

    D – E2